Sighting in Oregon WI that appeared very unusual and can't be explained.

We were walking on the bike path on the West side of Oregon WI that is along side County CC. We noticed a plane like craft that looked Silver in color, and it appeared to be at a high altitude like corporate jets usually travel at, maybe 50000 feet. There was no exhaust trail. We were walking along and talking, and looked up a few times. Then it was gone. It appeared to be traveling across our path at maybe a 45 degree angle from ground level. We continued looking for it for at least 5 minutes in a clear blue sky with no clouds. We were surprized it disappeared so quickly, and we were surprized there was no exhaust trail, although we have seen this before with some planes we thought they were probably corporate jets or military jets.